Gold nanorods core/AgPt alloy nanodots shell： A novel potent antibacterial nanostructure

In the light of the current problems of silver nanoparticles （Ag NPs） in terms of antibacterial performance, we have designed a novel trimetallic corelshell nanostructure with AgPt alloy nanodots epitaxially grown on gold nanorods （Au@PtAg NRs） as a potential antibacterial agent. Both Escherichia coli （E. coli） and Staphylococcus aureus （S. aureus） were studied. The antibacterial activity exhibits an obvious composition-dependence. On increasing the Ag fraction in the alloy shell up to 80%, the antibacterial activity gradually increases, demonstrating a flexible way to tune this activity. At 80% Ag, tile antibacterial activity is better than that of a pure Ag shell. The improved antibacterial ability mainly results from the high exposure of silver on the shell surface due to the dot morphology. We thus demonstrate that forming alloys is an effective way to improve antibacterial activity while retaining high chemical stability for Ag-based nanomaterials. Furthermore, due to the tunable localized surface plasmonic response in the near-infrared （NIR） spectral region, additional control over antibacterial activity using light--such as photothermal killing and photo- triggered silver ion release--is expected. As a demonstration, highly enhanced antibacterial activity is shown by utilizing the NIR photothermal effect of the nanostructures. Our results indicate that such tailored nanostructures will find a role in the future fight against bacteria, including the challenge of the increasing severity of multidrug resistance.

Rod-shaped Au@PtCu nanostructures with enhanced peroxidase-like activity and their ELISA application

Pt and its based alloy nanoparticles(NPs)have been reported to demonstrate novel enzyme-like activities.Varying composition is very important to realize the optimization of their functions through the tuning of electronic structure.In this paper,our effort is focused in this direction by tailoring the electronic structure of Pt NPs via alloying with copper.Using gold nanorod(Au NR)as core,a simple method to prepare PtCu alloy shell is developed(termed as Au@PtCu NR).The introduction of copper could result in endcap-preferred growth mode owing to the lattice mismatch between alloy shell and the Au core.The variation in the electronic structure changes the substrate affinity,and enhanced affinity was found for H2O2.Besides,the designed Au@PtCu nanostructures have realized spatial separation of catalytic and recognition sites.Binding of recognition antibodies had negligible effect on their catalytic activity.Based on their peroxidaselike activity,a highly sensitive detection of human immunoglobulin G(IgG)was demonstrated in a direct enzyme-linked immunosorbent assay(ELISA)mode.The detection limit can be as low as 90 pg/mL.